1895.] NATURAL SCIENCES OF PHILADELPHIA. 519 



15. Last dorsal segment yellow 16 



Last dorsal segment black 17 



16. Legs black; first dorsal segment not fasciate fuscus. 



Legs reddish, except base ; first dorsal segment fasciate. pygidialis. 



17. Mesosternum anteriorly sharply and strongly carinated; 



pygidium broad, not more than twice as long as its width 



in the middle 18 



Mesosternum anteriorly neither sharply nor strongly cari- 

 nated; pygidium long, narrow, somewhat more than twice 

 as long as its width in the middle (form very robust) . costalis. 



18. No distinct fuscous cloud in the second discoidal cell; front 



distinctly longer than broad; coxse and trochanters reddish, 



rarely obscure 19 



A distinct fuscous cloud filling the apical third of second dis- 

 coidal cell; front fully as broad as long; coxpe, trochanters 

 and femora in part, obscure nebulosus. 



19. Wings, excepting the usual fuscous cloud in the vicinity of 



the marginal cell, hyaline; enclosure of middle segment 



with 14-16 close-set ridges confertus. 



Wings fuscous, the cloud in the vicinity of the marginal cell 

 darker; enclosure of middle segment with 10-12 well- 

 separated ridges denticulatus. 



20. Middle segment more or less coarsely sculptured 2J 



Middle segment not coarsely sculptured, smooth 30 



21. Posterior surface of middle segment coarsely sculptured ... 22 

 Only the basal enclosure of middle segment coarsely sculp- 

 tured entirely or in part 27 



22. Wings with a strong yellow tinge on basal two-thirds .... 23 

 Wings not yellow basally 25 



23. Sculpture of enclosure of middle segment consisting of even, 



radiating ridges ; flagellum either entirely black, or with 



basal joints reddish 24 



Sculpture of enclosure of middle segment coarsely and irregu- 

 larly rugose; flagellum yellow beneath, black above (mark- 

 ings bright yellow; first joint of flagellum distinctly shorter 

 than the two following united) asperatus. 



24. Flagellum long, scarcely clavate, the first joint distinctly 



shorter than the two following united; clypeus entirely 



black; markings yellow atrifrons. 



Flagellum short, subclavate, the first joint but little longer 

 than the following two united; clypeus whitish basally; 

 marking whitish cdbosignatus. 



25. Femora, except apex, and the tibire in part, black; flagellum 



yellow beneath, black above 26 



Femora in greater part, tibia? and tarsi, reddish; flagellum 

 black, basal joints reddish (middle segment with two large 

 yellow spots) decorus. 



